import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.text.spi.DateFormatProvider;

/**
 * Created with IntelliJ IDEA.
 * Description:UDP服务器
 * User: wangxin
 * Date: 2024-08-12
 * Time: 15:15
 */
public class UDPEchoServer {
    private DatagramSocket socket = null;
    public  UDPEchoServer( int port) throws SocketException {
        socket = new DatagramSocket(port);
    }
    public void start() throws IOException {
        System.out.println("服务器启动！");
        while(true){
            //1.读取客户端的请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            //
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());
            // 2.根据请求计算响应，由于此处是服务器，响应就是请求。
            String reponse = process(request);
            //3.把响应写回客户端
            DatagramPacket reponsePacket = new DatagramPacket(reponse.getBytes(),reponse.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(reponsePacket);
            //4. 打印日志
            System.out.printf("[%s:%d] req=%s,req=%s\n",requestPacket.getAddress(),requestPacket.getPort(),
                    request,reponse);
        }
    }

    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UDPEchoServer server = new UDPEchoServer(9090);
        server.start();
    }
}
